Electronic fuel level warning device

ABSTRACT

An electronic system for providing a warning when the gasoline level in a fuel tank falls to a predetermined level. A flashing light indication warns the motorist when the predetermined level is reached. The flashing light is actuated through a silicon controlled rectifier by a float in the fuel tank provides a signal through an electronic assembly to activate the silicon controlled rectifier.

United States Patent Whalen et al.

[ 1 Aug. 1, 1972 [54] ELECTRONIC FUEL LEVEL WARNING DEVICE [72]Inventors: George J. Whalen, 612 Woodland Hills, White Plains, NY.10604; Rudolf F. Graf, lll Van Etten Blvd, New Rochelle, NY. 14620 22]Filed: Aug. 5, 1910 21 Appl.No.: 61,377

[52] U.S. Cl. ..340/59, 340/244 B [51] Int. Cl. ..B60q 1/00 [58] Fieldof Search ..340/59, 244 B, 8] F;

307/252 H, 252 J, 10 R [56] References Cited UNITED STATES PATENTS3,333,469 8/1967 Godfrey ..340/244B FROM IGNITION SWITCH 2,892,996 6/1959 Hollins ..340/81 F 2,835,885 5/1958 Boddy ..340/59 3,461,345 8/1969Gilbert ..307/252.5l

Primary Examiner-John W. Caldwell Assistant Examiner-Glen R. Swann, IllAttorneyKenneth S. Goldfarb 57 ABSTRACT An electronic system forproviding a warning when the gasoline level in a fuel tank falls to apredetermined level. A flashing light indication warns the motorist whenthe predetermined level is reached. The flashing light is actuatedthrough a silicon controlled rectifier by a float in the fuel tankprovides a signal through an electronic assembly to activate the siliconcontrolled rectifier.

3 Clains, 1 Drawing Figure REGULATOR T T T T "'l LTHERMOSTATIC VOLTAGEPATENTEDAUG 1 I972 FROM IGNITION SWITCH INVENTORS GEORGE J. WHLLENVOLTAGE THE RMOSTATIC REGULATOR RUDOLF F. GRAF AT ORNEY ELECTRONIC FUELLEVEL WARNING DEVICE BACKGROUND OF THE INVENTION This invention relatesto a warning system and, more particularly, to a warning systemproviding a flashing visual signal when the, fuel level in a fuel tankfalls to a provided which is activated by the motorist when the maintank becomes empty. In a sense, the reserve tank system provides adiscrete indication of the level, while the more common fuel guagesprovide a steady visual indication of the level.

An object of the present invention is to provide an improved warningsystem when fuel in a tank drops to a predetermined level.

Another object of the present invention is to provide an improved visualwarning signal which will effectively call attention to the sensedcondition.

Still another object of the present invention is to provide a compact,sturdy and efficient warning system.

Another object of the present invention is to provide a warning systemsuitable for easy installation in automobiles.

Still another object of the present invention is to provide a reliableelectronic warning system.

SUMMARY OF THE INVENTION In accordance with the principles of thepresent invention, the-above objects are accomplished by providing awarning system including first means for sensing the fuel level, secondmeans for triggering a flashing light when the fuel falls below apredetermined level, and third means for terminating the operation ofthe flashing light when the fuel rises above the predetermined level. Afloat in the fuel tank is connected to the wiper arm of a variableresistor. As the fuel falls to the predetermined level a pulse ofcorrespondingly varied amplitude is delivered to the gate electrode of asilicon controlled rectifier (SCR). A self-flashing lamp is connected tothe SCR and flashes when the SCR is triggered into its conducting state.As the tank is replenished, the float rises lowering the pulse leveldelivered to the SCR which fails to trigger it into its conductingstate.

The accompanying FIGURE is a schematic diagram of an embodiment of thepresent invention. DETAILED DESCRIPTION The electronic warning system ofthe present invention may find wide applicability in many different typefuel systems. For purposes of illustration, it will be described withreference to an automobile being provided with a l2-volt system.

The negative electrode of the 12 volt power supply is connected toground while the positive electrode 12 is connected to one side ofthermostatic voltage regulator 14 and to one side 15 of a selflflashinglamp 16. Both thermostatic voltage regulator 14 and self-flashing lamp16 are well known devices with the lamp, preferably, having a built-inthermal switch which opens and closes as a function of the lamp filamenttemperature. The other side of regulator 14 is connected through anindicator gauge 18, such as a gasoline gauge to the wiper arm 20 of avariable resistor 22 and to one side of a wave shaping network 24 andvoltage dividing network 26. One end 23 of variable resistor 22 isconnected to ground while the other end 25 is floating. The gauge 18,preferably, is a thermally ac tuated gauge maintaining a stable readingupon receiving periodic pulses of current from regulator 14. A float 28which rests on top of the liquid or fuel and provides an indication ofthe fuel level controls the position of wiper arm 20. It will berecognized by those skilled in the art that regulator 14, gauge 18,.variable resistor 22, and float 28, all enclosed within the dottedlines, are standard elements in an automobile.

The wave shaping network 24 comprises a parallel combination of aresistor 30 and a capacitor 32. One

side of this parallel combination is connected to the above describedwiper arm 20 while the other side of this parallel combination 24 isconnected to the variable arm 34 of a potentiometer 36. One end 38 ofpotentiometer 36 is connected to the gate terminal 42 of a gatedsemi-conductor device, preferably, a silicon controlled rectifier (SCR)44. A silicon-controlled rectifier is a latching type relay whichnormally is not conducting. When triggered into its conducting state, itwill continue conducting until the current passingfrom its anode tocathode falls below a predetermined level. It will not conduct againuntil properly triggered, which is independent of the anode to cathodevoltage. A bridging capacitor 46 is connected between the anode andcathode terminals of SCR 44 while the other side 48 of the flashing lampis connected to the anode terminal of SCR 44. The cathode terminal ofSCR 44 is connected to ground.

While the above sets forth a description of the elements illustratingthe principles of the present invention, the following describes itsoperation. When the fuel tank is full, the wiper arm 20 is near theground side 23 of the resistor 22, and little or no voltage is developedacross resistor 22. As fuel is consumed and the fuel level falls, thefloat 28 moves wiper arm 20 away from the ground terminal 23 increasingthe voltage developed across resistor 22. Simultaneously, currentthrough the visual gauge 18 is decreased presenting a visual readout ofthe fuel level to the motorist.

Thermostatic voltageregulator l4 periodically emits a pulse of currentthrough the gauge 18 maintaining a stable reading on the gauge. Voltagedivider network 26 senses the pulse amplitude across resistor 22, and aportion thereof appears across resistor 36. Variable resistor 36 enablesthe trigger point corresponding to a predetermined fuel level to beselected by the motorist. When the magnitude of the pulse amplitudeappearing across resistor 36 is at a predetermined triggering level, theSCR 44 is triggered into its conducting state permitting current to flowfrom the twelve volt supply through self-flashing lamp l6 and SCR 44.When the lamp flashes, current ceases to flow through it because of itsbuilt-in'thermal actuation, but SCR 44 will again wiper arms 20 and 34has a relatively fast time constant thereby sharpening the pulse appliedto the gate electrode 40 of SCR 44.

A latitude of modification, substitution and change is intended in theforegoing disclosure, and in some instances, some features of theinvention will be employed without a corresponding use of otherfeatures.

We claim:

1. A level sensing warning system for use with a tank having a liquidtherein and for providing a warning when the level of a liquid held in atank reaches a predetermined level comprising visual warning means forproviding a visual warning when said liquid reaches said predeterminedlevel, first means for sensing the level of said liquid, said firstmeans including a variable resistor provided with a wiper arm, secondmeans responsive to said first means for actuating said visual warningmeans when said liquid reaches said predetermined level, said warningmeans including flashing lamp means for providing a flashing visualsignal, a silicon controlled rectifier device having a gate terminal,said device being triggered into a conducting state when a signal fromsaid second means of a predetermined amplitude is applied to said gateterminal, said device being connected to said flashing lamp means, saidfirst means being provided with a source or periodic pulses supplied tosaid wiper arm so that a pulse amplitude level is developed across saidvariable resistor responsive to the level of said liquid, said pulsedeveloped across said variable resistor being supplied to said secondmeans, said second means being connected for supplying a pulse to saidgate terminal, so that when said liquid is at said predetermined levelsaid device is triggered into its conducting state actuating saidwarning means, said second means being provided with wave shaping meansconnected between said wiper arm and said gate electrode for shaping thepulse appearing at said gate terminal.

2. A level sensing warning system as set forth in claim 1, wherein saidwave shaping means includes a resistor and a capacitor connected inparallel.

3. A level sensing warning system as set forth in claim I, wherein saidflashing lamp is provided with a thermal switch for turning said lampofi' after it is turned on, said liquid being gasoline and said tankbeing a gasoline fuel tank, said first means being provided with a fuelguage connected between said source of periodic pulses and said wiperarm, a float resting on top of said gasoline in said fuel tank, saidfloat being connected to said wiper arm, and said second means beingprovided with a variable resistor for adjusting the amplitude of thepulse supplied to said gate terminal.

1. A Level sensing warning system for use with a tank having a liquidtherein and for providing a warning when the level of a liquid held in atank reaches a predetermined level comprising visual warning means forproviding a visual warning when said liquid reaches said predeterminedlevel, first means for sensing the level of said liquid, said firstmeans including a variable resistor provided with a wiper arm, secondmeans responsive to said first means for actuating said visual warningmeans when said liquid reaches said predetermined level, said warningmeans including flashing lamp means for providing a flashing visualsignal, a silicon controlled rectifier device having a gate terminal,said device being triggered into a conducting state when a signal fromsaid second means of a predetermined amplitude is applied to said gateterminal, said device being connected to said flashing lamp means, saidfirst means being provided with a source or periodic pulses supplied tosaid wiper arm so that a pulse amplitude level is developed across saidvariable resistor responsive to the level of said liquid, said pulsedeveloped across said variable resistor being supplied to said secondmeans, said second means being connected for supplying a pulse to saidgate terminal, so that when said liquid is at said predetermined levelsaid device is triggered into its conducting state actuating saidwarning means, said second means being provided with wave shaping meansconnected between said wiper arm and said gate electrode for shaping thepulse appearing at said gate terminal.
 2. A level sensing warning systemas set forth in claim 1, wherein said wave shaping means includes aresistor and a capacitor connected in parallel.
 3. A level sensingwarning system as set forth in claim 1, wherein said flashing lamp isprovided with a thermal switch for turning said lamp off after it isturned on, said liquid being gasoline and said tank being a gasolinefuel tank, said first means being provided with a fuel guage connectedbetween said source of periodic pulses and said wiper arm, a floatresting on top of said gasoline in said fuel tank, said float beingconnected to said wiper arm, and said second means being provided with avariable resistor for adjusting the amplitude of the pulse supplied tosaid gate terminal.